US20230377851A1 - Etching method and plasma processing apparatus - Google Patents
Etching method and plasma processing apparatus Download PDFInfo
- Publication number
- US20230377851A1 US20230377851A1 US18/319,419 US202318319419A US2023377851A1 US 20230377851 A1 US20230377851 A1 US 20230377851A1 US 202318319419 A US202318319419 A US 202318319419A US 2023377851 A1 US2023377851 A1 US 2023377851A1
- Authority
- US
- United States
- Prior art keywords
- gas
- region
- process gas
- substrate
- etching method
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Pending
Links
- 238000000034 method Methods 0.000 title claims abstract description 143
- 238000005530 etching Methods 0.000 title claims abstract description 80
- 238000012545 processing Methods 0.000 title claims description 88
- 230000008569 process Effects 0.000 claims abstract description 93
- 239000000758 substrate Substances 0.000 claims abstract description 86
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 claims abstract description 21
- 229910052814 silicon oxide Inorganic materials 0.000 claims abstract description 21
- 229910052581 Si3N4 Inorganic materials 0.000 claims abstract description 12
- HQVNEWCFYHHQES-UHFFFAOYSA-N silicon nitride Chemical compound N12[Si]34N5[Si]62N3[Si]51N64 HQVNEWCFYHHQES-UHFFFAOYSA-N 0.000 claims abstract description 12
- 239000002356 single layer Substances 0.000 claims abstract description 8
- 239000007789 gas Substances 0.000 claims description 262
- 125000004216 fluoromethyl group Chemical group [H]C([H])(F)* 0.000 claims description 16
- 229910052799 carbon Inorganic materials 0.000 claims description 13
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims description 7
- 239000011261 inert gas Substances 0.000 claims description 7
- 229910052760 oxygen Inorganic materials 0.000 claims description 7
- 239000001301 oxygen Substances 0.000 claims description 7
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 5
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 claims description 3
- 229910052796 boron Inorganic materials 0.000 claims description 3
- 238000002474 experimental method Methods 0.000 description 34
- 230000006870 function Effects 0.000 description 9
- 239000000919 ceramic Substances 0.000 description 6
- 230000007246 mechanism Effects 0.000 description 6
- 230000001681 protective effect Effects 0.000 description 6
- 238000004891 communication Methods 0.000 description 5
- RWRIWBAIICGTTQ-UHFFFAOYSA-N difluoromethane Chemical compound FCF RWRIWBAIICGTTQ-UHFFFAOYSA-N 0.000 description 5
- 102100021277 Beta-secretase 2 Human genes 0.000 description 4
- 101710150190 Beta-secretase 2 Proteins 0.000 description 4
- NBVXSUQYWXRMNV-UHFFFAOYSA-N fluoromethane Chemical compound FC NBVXSUQYWXRMNV-UHFFFAOYSA-N 0.000 description 4
- 125000002023 trifluoromethyl group Chemical group FC(F)(F)* 0.000 description 4
- 230000000694 effects Effects 0.000 description 3
- 229910052743 krypton Inorganic materials 0.000 description 3
- DNNSSWSSYDEUBZ-UHFFFAOYSA-N krypton atom Chemical compound [Kr] DNNSSWSSYDEUBZ-UHFFFAOYSA-N 0.000 description 3
- 238000012546 transfer Methods 0.000 description 3
- 229910003481 amorphous carbon Inorganic materials 0.000 description 2
- 238000010586 diagram Methods 0.000 description 2
- 125000001028 difluoromethyl group Chemical group [H]C(F)(F)* 0.000 description 2
- 125000001153 fluoro group Chemical group F* 0.000 description 2
- 239000011810 insulating material Substances 0.000 description 2
- -1 monofluoromethyl group Chemical group 0.000 description 2
- 229920006254 polymer film Polymers 0.000 description 2
- 230000001360 synchronised effect Effects 0.000 description 2
- BSYNRYMUTXBXSQ-UHFFFAOYSA-N Aspirin Chemical compound CC(=O)OC1=CC=CC=C1C(O)=O BSYNRYMUTXBXSQ-UHFFFAOYSA-N 0.000 description 1
- 229910052580 B4C Inorganic materials 0.000 description 1
- 229910052582 BN Inorganic materials 0.000 description 1
- 102100021257 Beta-secretase 1 Human genes 0.000 description 1
- 101710150192 Beta-secretase 1 Proteins 0.000 description 1
- PZNSFCLAULLKQX-UHFFFAOYSA-N Boron nitride Chemical compound N#B PZNSFCLAULLKQX-UHFFFAOYSA-N 0.000 description 1
- 230000002159 abnormal effect Effects 0.000 description 1
- 238000007792 addition Methods 0.000 description 1
- 230000008901 benefit Effects 0.000 description 1
- 238000005513 bias potential Methods 0.000 description 1
- INAHAJYZKVIDIZ-UHFFFAOYSA-N boron carbide Chemical compound B12B3B4C32B41 INAHAJYZKVIDIZ-UHFFFAOYSA-N 0.000 description 1
- 239000012267 brine Substances 0.000 description 1
- 239000004020 conductor Substances 0.000 description 1
- 238000010494 dissociation reaction Methods 0.000 description 1
- 230000005593 dissociations Effects 0.000 description 1
- 239000013529 heat transfer fluid Substances 0.000 description 1
- 238000009616 inductively coupled plasma Methods 0.000 description 1
- 239000000463 material Substances 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052756 noble gas Inorganic materials 0.000 description 1
- 229910052710 silicon Inorganic materials 0.000 description 1
- 239000010703 silicon Substances 0.000 description 1
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
- 229910052721 tungsten Inorganic materials 0.000 description 1
- UONOETXJSWQNOL-UHFFFAOYSA-N tungsten carbide Chemical compound [W+]#[C-] UONOETXJSWQNOL-UHFFFAOYSA-N 0.000 description 1
Images
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32431—Constructional details of the reactor
- H01J37/3244—Gas supply means
- H01J37/32449—Gas control, e.g. control of the gas flow
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
- H01J37/32—Gas-filled discharge tubes
- H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
- H01J37/32082—Radio frequency generated discharge
- H01J37/32091—Radio frequency generated discharge the radio frequency energy being capacitively coupled to the plasma
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31105—Etching inorganic layers
- H01L21/31111—Etching inorganic layers by chemical means
- H01L21/31116—Etching inorganic layers by chemical means by dry-etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/02—Manufacture or treatment of semiconductor devices or of parts thereof
- H01L21/04—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer
- H01L21/18—Manufacture or treatment of semiconductor devices or of parts thereof the devices having potential barriers, e.g. a PN junction, depletion layer or carrier concentration layer the devices having semiconductor bodies comprising elements of Group IV of the Periodic Table or AIIIBV compounds with or without impurities, e.g. doping materials
- H01L21/30—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26
- H01L21/31—Treatment of semiconductor bodies using processes or apparatus not provided for in groups H01L21/20 - H01L21/26 to form insulating layers thereon, e.g. for masking or by using photolithographic techniques; After treatment of these layers; Selection of materials for these layers
- H01L21/3105—After-treatment
- H01L21/311—Etching the insulating layers by chemical or physical means
- H01L21/31144—Etching the insulating layers by chemical or physical means using masks
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L21/00—Processes or apparatus adapted for the manufacture or treatment of semiconductor or solid state devices or of parts thereof
- H01L21/67—Apparatus specially adapted for handling semiconductor or electric solid state devices during manufacture or treatment thereof; Apparatus specially adapted for handling wafers during manufacture or treatment of semiconductor or electric solid state devices or components ; Apparatus not specifically provided for elsewhere
- H01L21/67005—Apparatus not specifically provided for elsewhere
- H01L21/67011—Apparatus for manufacture or treatment
- H01L21/67017—Apparatus for fluid treatment
- H01L21/67063—Apparatus for fluid treatment for etching
- H01L21/67069—Apparatus for fluid treatment for etching for drying etching
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
- H01J2237/32—Processing objects by plasma generation
- H01J2237/33—Processing objects by plasma generation characterised by the type of processing
- H01J2237/334—Etching
Definitions
- Exemplary embodiments of the present disclosure relate to an etching method and a plasma processing apparatus.
- Japanese Unexamined Patent Publication No. 2016-51750 discloses a method of etching a first region having a multilayer film formed by alternately providing a silicon oxide film and a silicon nitride film and a second region having a single-layer silicon oxide film. According to the etching method disclosed in Japanese Unexamined Patent Publication No. 2016-51750, a step of generating a plasma of a first process gas containing hydrofluorocarbon and a step of generating a plasma of a second process gas containing fluorocarbon are repeated alternately.
- an etching method includes (a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask on the first region and the second region; (b) etching the substrate with a first plasma generated from a first process gas; and (c) etching the substrate with a second plasma generated from a second process gas different from the first process gas, wherein the first process gas contains a C v1 F w1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond, and the second process gas contains a C x1 H y1 F z1 (x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more) gas containing an unsaturated bond.
- FIG. 1 is a schematic diagram illustrating a plasma processing apparatus according to an exemplary embodiment.
- FIG. 2 is a schematic diagram illustrating the plasma processing apparatus according to an exemplary embodiment.
- FIG. 3 is a flowchart illustrating an etching method according to an exemplary embodiment.
- FIG. 4 is a cross-sectional view of an example substrate to which the method of FIG. 3 can be applied.
- FIG. 5 is a cross-sectional view of an example substrate after the method of FIG. 3 has been applied.
- FIG. 6 is a cross-sectional view of a substrate having a recess having an example aspect ratio.
- An etching method includes (a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask on the first region and the second region; (b) etching the substrate with a first plasma generated from a first process gas; and (c) etching the substrate with a second plasma generated from a second process gas different from the first process gas, wherein the first process gas contains a C v1 F w1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond, and the second process gas contains a C x1 H y1 F z1 (x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more) gas containing an unsaturated bond.
- the mechanism is considered as follows, the mechanism is not limited to this.
- higher-order radicals are generated from unsaturated bonds contained in the first process gas and the second process gas, respectively.
- Higher-order radicals have high molecular weights, so the higher-order radicals tend to form a deposited film on the surface of the mask. As a result, it is possible to improve the etching selectivity of the first region and the second region with respect to the mask.
- the etching method may further include (d) repeating (b) and (c) alternately. In this case, it is possible to increase the depth of a recess formed in the first region and the depth of a recess formed in the second region.
- the first process gas may further contain a C x2 H y2 F z2 (x2 is an integer of 2 or more, and y2 and z2 are integers of 1 or more) gas containing an unsaturated bond
- the second process gas may further contain a C v2 F w2 (v2 is an integer of 2 or more, and w2 is an integer of 1 or more) gas containing an unsaturated bond
- a ratio of a flow rate of the C v1 F w1 gas to a flow rate of the C x2 H y2 F z2 gas may be greater than a ratio of a flow rate of the C v2 F w2 gas to a flow rate of the C x1 H y1 F z1 gas.
- a fluorocarbon gas has an etching rate with respect to a silicon oxide film, which is higher than an etching rate with respect to a silicon nitride film.
- Hydrofluorocarbon has an etching rate with respect to the silicon nitride film, which is higher than an etching rate with respect to the silicon oxide film.
- the ratio of the flow rate of the C v1 F w1 gas to the flow rate of the C x2 H y2 F z2 gas may be 1 or more and 2 or less.
- the ratio of the flow rate of the C v2 F w2 gas to the flow rate of the C x1 H y1 F z1 gas may be less than 1.
- the C v1 F w1 gas may contain a fluoromethyl group.
- a lower-order radical is generated from the fluoromethyl group. Since the lower-order radicals have low molecular weights, the lower-order radicals can go deep into a recess formed by etching. Thus, it is possible to form a deep recess by etching.
- the C v1 F w1 gas may contain at least one of C 4 F 8 or C 3 F 6 .
- the C x1 H y1 F z1 gas may contain a fluoromethyl group.
- lower-order radicals are generated from the fluoromethyl group. Since the lower-order radicals have low molecular weights, the lower-order radicals can go deep into a recess formed by etching. Thus, it is possible to form a deep recess by etching.
- the C x1 H y1 F z1 gas may contain at least one of C 3 H 2 F 4 or C 4 H 2 F 6 .
- the C v1 F w1 gas may contain C 3 F 6
- the C x1 H y1 F z1 gas may contain C 3 H 2 F 4 .
- a pressure in the chamber in (b) may be higher than a pressure in the chamber in (c).
- a processing time of (b) may be longer than a processing time of (c).
- a ratio of the processing time of (b) to the processing time of (c) may be more than 1 and 3 or less.
- an aspect ratio of a recess formed in the first region and an aspect ratio of a recess formed in the second region in the substrate after the etching method has been applied may be equal to or more than 10.
- At least one of the first process gas or the second process gas may further contain an oxygen-containing gas.
- the mask may contain at least one of carbon or boron.
- a plasma processing apparatus includes a chamber; a substrate support for supporting a substrate in the chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask on the first region and the second region; a gas supply configured to supply a first process gas and a second process gas different from the first process gas into the chamber; a plasma generator configured to generate a first plasma and a second plasma from the first process gas and the second process gas in the chamber, respectively; and a controller, wherein the first process gas contains a C v1 F w1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond, the second process gas contains a C x1 H y1 F z1 (x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more) gas containing an unsaturated bond
- FIG. 1 illustrates an example configuration of a plasma processing system.
- the plasma processing system includes a plasma processing apparatus 1 and a controller 2 .
- the plasma processing system is an example substrate processing system
- the plasma processing apparatus 1 is an example substrate processing apparatus.
- the plasma processing apparatus 1 includes a plasma processing chamber 10 , a substrate support 11 , and a plasma generator 12 .
- the plasma processing chamber 10 has a plasma processing space.
- the plasma processing chamber 10 further has at least one gas inlet for supplying at least one process gas into the plasma processing space and at least one gas outlet for exhausting gases from the plasma processing space.
- the gas inlet is connected to a gas supply 20 described below and the gas outlet is connected to a gas exhaust system 40 described below.
- the substrate support 11 is disposed in a plasma processing space and has a substrate supporting surface for supporting a substrate.
- the plasma generator 12 is configured to generate a plasma from the at least one process gas supplied into the plasma processing space.
- the plasma formed in the plasma processing space may be, for example, a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron-cyclotron-resonance (ECR) plasma, a helicon wave plasma (HWP), or a surface wave plasma (SWP).
- Various types of plasma generators may also be used, such as an alternating current (AC) plasma generator and a direct current (DC) plasma generator.
- AC signal (AC power) used in the AC plasma generator has a frequency in a range of 100 kHz to 10 GHz.
- examples of the AC signal include a radio frequency (RF) signal and a microwave signal.
- the RF signal has a frequency in a range of 100 kHz to 150 MHz.
- the controller 2 processes computer executable instructions causing the plasma processing apparatus 1 to perform various steps described in this disclosure.
- the controller 2 may be configured to control individual components of the plasma processing apparatus 1 such that these components execute the various steps.
- the functions of the controller 2 may be partially or entirely incorporated into the plasma processing apparatus 1 .
- the controller 2 may include a processor 2 a 1 , a storage 2 a 2 , and a communication interface 2 a 3 .
- the controller 2 is implemented in, for example, a computer 2 a .
- the processor 2 a 1 may be configured to read a program from the storage 2 a 2 , and then perform various controlling operations by executing the program. This program may be preliminarily stored in the storage 2 a 2 or retrieved from any medium, as appropriate.
- the resulting program is stored in the storage 2 a 2 , and then the processor 2 a 1 reads to execute the program from the storage 2 a 2 .
- the medium may be of any type which can be accessed by the computer 2 a or may be a communication line connected to the communication interface 2 a 3 .
- the processor 2 a 1 may be a central processing unit (CPU).
- the storage 2 a 2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or any combination thereof.
- the communication interface 2 a 3 can communicate with the plasma processing apparatus 1 via a communication line, such as a local area network (LAN).
- LAN local area network
- FIG. 2 illustrates the example configuration of the capacitively coupled plasma processing apparatus.
- the capacitively coupled plasma processing apparatus 1 includes a plasma processing chamber 10 , a gas supply 20 , an electric power source 30 , and a gas exhaust system 40 .
- the plasma processing apparatus 1 further includes a substrate support 11 and a gas introduction unit.
- the gas introduction unit is configured to introduce at least one process gas into the plasma processing chamber 10 .
- the gas introduction unit includes a showerhead 13 .
- the substrate support 11 is disposed in a plasma processing chamber 10 .
- the showerhead 13 is disposed above the substrate support 11 .
- the showerhead 13 functions as at least part of the ceiling of the plasma processing chamber 10 .
- the plasma processing chamber 10 has a plasma processing space 10 s that is defined by the showerhead 13 , the sidewall 10 a of the plasma processing chamber 10 , and the substrate support 11 .
- the plasma processing chamber 10 is grounded.
- the showerhead 13 and the substrate support 11 are electrically insulated from the housing of the plasma processing chamber 10 .
- the substrate support 11 includes a body 111 and a ring assembly 112 .
- the body 111 has a central region 111 a for supporting a substrate V and an annular region 111 b for supporting the ring assembly 112 .
- An example of the substrate W is a wafer.
- the annular region 111 b of the body 111 surrounds the central region 111 a of the body 111 in plan view.
- the substrate W is disposed on the central region 111 a of the body 111
- the ring assembly 112 is disposed on the annular region 111 b of the body 111 so as to surround the substrate W on the central region 111 a of the body 111 .
- the central region 111 a is also called a substrate supporting surface for supporting the substrate W
- the annular region 111 b is also called a ring supporting surface for supporting the ring assembly 112 .
- the body 111 includes a base 1110 and an electrostatic chuck 1111 .
- the base 1110 includes a conductive member.
- the conductive member of the base 1110 can function as a lower electrode.
- the electrostatic chuck 1111 is disposed on the base 1110 .
- the electrostatic chuck 1111 includes a ceramic member 1111 a and an electrostatic electrode 1111 b disposed in the ceramic member 1111 a .
- the ceramic member 1111 a has the central region 111 a .
- the ceramic member 1111 a also has the annular region 111 b . Any other member, such as an annular electrostatic chuck or an annular insulting member, surrounding the electrostatic chuck 1111 may have the annular region 111 b .
- the ring assembly 112 may be disposed on either the annular electrostatic chuck or the annular insulating member, or both the electrostatic chuck 1111 and the annular insulating member.
- At least one RF/DC electrode coupled to an RF source 31 and/or a DC source 32 described below may be disposed in the ceramic member 1111 a .
- the at least one RF/DC electrode functions as the lower electrode. If a bias RF signal and/or DC signal described below are supplied to the at least one RF/DC electrode, the RF/DC electrode is also called a bias electrode.
- the conductive member of the base 1110 and the at least one RF/DC electrode may each function as a lower electrode.
- the electrostatic electrode 1111 b may also be function as a lower electrode.
- the substrate support 11 accordingly includes at least one lower electrode.
- the ring assembly 112 includes one or more annular members.
- the annular members include one or more edge rings and at least one cover ring.
- the edge ring is composed of a conductive or insulating material, whereas the cover ring is composed of an insulating material.
- the substrate support 11 may also include a temperature adjusting module that is configured to adjust at least one of the electrostatic chuck 1111 , the ring assembly 112 , and the substrate to a target temperature.
- the temperature adjusting module may be a heater, a heat transfer medium, a flow passage 1110 a , or any combination thereof.
- the flow passage 1110 a is formed in the base 1110 , one or more heaters are disposed in the ceramic member 1111 a of the electrostatic chuck 1111 .
- the substrate support 11 may further include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the rear surface of the substrate W and the central region 111 a.
- the showerhead 13 is configured to introduce at least one process gas from the gas supply 20 into the plasma processing space 10 s .
- the showerhead 13 has at least one gas inlet 13 a , at least one gas diffusing space 13 b , and a plurality of gas feeding ports 13 c .
- the process gas supplied to the gas inlet 13 a passes through the gas diffusing space 13 b and is then introduced into the plasma processing space 10 s from the gas feeding ports 13 c .
- the showerhead 13 further includes at least one upper electrode.
- the gas introduction unit may include one or more side gas injectors provided at one or more openings formed in the sidewall 10 a , in addition to the showerhead 13 .
- the gas supply 20 may include at least one gas source 21 and at least one flow controller 22 .
- the gas supply 20 is configured to supply at least one process gas from the corresponding gas source 21 through the corresponding flow controller 22 into the showerhead 13 .
- Each flow controller 22 may be, for example, a mass flow controller or a pressure-controlled flow controller.
- the gas supply 20 may include a flow modulation device that can modulate or pulse the flow of the at least one process gas.
- the electric power source 30 include an RF source 31 coupled to the plasma processing chamber 10 through at least one impedance matching circuit.
- the RF source 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and/or at least one upper electrode.
- a plasma is thereby formed from at least one process gas supplied into the plasma processing space 10 s .
- the RF source 31 can function as at least part of the plasma generator 12 .
- the bias RF signal supplied to the at least one lower electrode causes a bias potential to occur in the substrate W, which potential then attracts ionic components in the plasma to the substrate W.
- the RF source 31 includes a first RF generator 31 a and a second RF generator 31 b .
- the first RF generator 31 a is coupled to the at least one lower electrode and/or the at least one upper electrode through the at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for generating a plasma.
- the source RF signal has a frequency in a range of 10 MHz to 150 MHz.
- the first RF generator 31 a may be configured to generate two or more source RF signals having different frequencies. The resulting source RF signal(s) is supplied to the at least one lower electrode and/or the at least one upper electrode.
- the second RF generator 31 b is coupled to the at least one lower electrode through the at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power).
- the bias RF signal and the source RF signal may have the same frequency or different frequencies.
- the bias RF signal has a frequency which is less than that of the source RF signal.
- the bias RF signal has a frequency in a range of 100 kHz to 60 MHz.
- the second RF generator 31 b may be configured to generate two or more bias RF signals having different frequencies.
- the resulting bias RF signal(s) is supplied to the at least one lower electrode.
- at least one of the source RF signal and the bias RF signal may be pulsed.
- the electric power source 30 may also include a DC source 32 coupled to the plasma processing chamber 10 .
- the DC source 32 includes a first DC generator 32 a and a second DC generator 32 b .
- the first DC generator 32 a is connected to the at least one lower electrode and is configured to generate a first DC signal.
- the resulting first DC signal is applied to the at least one lower electrode.
- the second DC generator 32 b is connected to the at least one upper electrode and is configured to generate a second DC signal.
- the resulting second DC signal is applied to the at least one upper electrode.
- the first and second DC signals may be pulsed.
- a sequence of voltage pulses is applied to the at least one lower electrode and/or the at least one upper electrode.
- the voltage pulses have rectangular, trapezoidal, or triangular waveform, or a combined waveform thereof.
- a waveform generator for generating a sequence of voltage pulses from the DC signal is disposed between the first DC generator 32 a and the at least one lower electrode.
- the first DC generator 32 a and the waveform generator thereby functions as a voltage pulse generator.
- the voltage pulse generator is connected to the at least one upper electrode.
- the voltage pulse may have positive polarity or negative polarity.
- a sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses in a cycle.
- the first and second DC generators 32 a , 32 b may be disposed in addition to the RF source 31 , or the first DC generator 32 a may be disposed in place of the second RF generator 31 b.
- the gas exhaust system 40 may be connected to, for example, a gas outlet 10 e provided in the bottom wall of the plasma processing chamber 10 .
- the gas exhaust system 40 may include a pressure regulation valve and a vacuum pump.
- the pressure regulation valve enables the pressure in the plasma processing space 10 s to be adjusted.
- the vacuum pump may be a turbo-molecular pump, a dry pump, or a combination thereof.
- FIG. 3 is a flowchart illustrating an etching method according to an exemplary embodiment.
- An etching method MT (referred to as a “method MT” below) illustrated in FIG. 3 can be performed by the plasma processing apparatus 1 in the above embodiment.
- the method MT can be applied to a substrate W.
- FIG. 4 is a cross-sectional view of an example substrate to which the method of FIG. 3 can be applied.
- the substrate W includes a first region R 1 , a second region R 2 , and a mask MK.
- the mask MK is on the first region R 1 and the second region R 2 .
- the substrate W may include an underlying region UR.
- the first region R 1 and the second region R 2 may be provided on the underlying region UR.
- the first region R 1 has a multilayer film in which silicon oxide films L 1 and silicon nitride films L 2 are alternately stacked.
- the silicon oxide film L 1 may be located on each of the top surface and the bottom surface of the first region R 1 .
- the second region R 2 has a single-layer silicon oxide film.
- the first region R 1 and the second region R 2 may be arranged in a direction along the main surface of the substrate W. In a direction perpendicular to the main surface of the substrate W, the first region R 1 may have the same thickness as the second region R 2 .
- Each of the first region R 1 and the second region R 2 may be a film for a memory device such as a 3D-NAND.
- the mask MK may have an opening OP 1 over the first region R 1 and an opening OP 2 over the second region R 2 .
- the mask MK may contain at least one of carbon or boron.
- the mask MK may contain at least one of spin-on carbon, tungsten carbide, or amorphous carbon.
- the mask MK may contain at least one of boron nitride or boron carbide.
- the underlying region UR may contain at least one of silicon, organic (carbon-containing) material, or metal.
- FIG. 5 is a cross-sectional view of an example substrate after the method of FIG. 3 has been applied.
- the method MT can be performed in the plasma processing apparatus 1 in a manner that the controller 2 controls each unit of the plasma processing apparatus 1 .
- the substrate W on a substrate support 11 disposed in a plasma processing chamber 10 is processed.
- the method MT can include Steps ST 1 to ST 4 .
- Steps ST 1 to ST 4 can be performed in order.
- the method MT may not include Step ST 4 .
- Step ST 3 may be performed before Step ST 2 .
- Step ST 1 the substrate W illustrated in FIG. 4 is on the substrate support 11 in the plasma processing chamber 10 .
- the underlying region UR can be disposed between the first region R 1 or the second region R 2 , and the substrate support 11 .
- Step ST 2 the substrate W is etched with a first plasma generated from a first process gas.
- a recess corresponding to the opening OP 1 of the mask MK can be formed in the first region R 1 .
- a recess corresponding to the opening OP 2 of the mask MK can be formed in the second region R 2 .
- the first process gas contains a C v1 F w1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond.
- the C v1 F w1 gas is a fluorocarbon gas.
- the unsaturated bond may include a carbon double bond or a carbon triple bond.
- the C v1 F w1 gas may contain a plurality of unsaturated bonds.
- the C v1 F w1 gas may contain a fluorine substituent.
- the C v1 F w1 gas may contain a fluoromethyl group (—CF x ).
- the C v1 F w1 gas may contain a plurality of fluoromethyl groups.
- the fluoromethyl group may be a monofluoromethyl group, a difluoromethyl group, or a trifluoromethyl group.
- the C v1 F w1 gas may contain at least one of C 4 F 8 or C 3 F 6 . Each of C 4 F 8 and C 3 F 6 contains one double bond and one trifluoromethyl group.
- the first process gas may further contain a C x2 H y2 F z2 (x2 is an integer of 2 or more, and y2 and z2 are integers of 1 or more) gas containing an unsaturated bond.
- the C x2 H y2 F z2 gas is a hydrofluorocarbon gas.
- the unsaturated bond may include a carbon double bond or a carbon triple bond.
- the C x2 H y2 F z2 gas may contain a plurality of unsaturated bonds.
- the C x2 H y2 F z2 gas may contain a fluorine substituent.
- the C x2 H y2 F z2 gas may contain a fluoromethyl group (—CF x ).
- the C x2 H y2 F z2 gas may contain a plurality of fluoromethyl groups.
- the fluoromethyl group may be a monofluoromethyl group, a difluoromethyl group, or a trifluoromethyl group.
- the C x2 H y2 F z2 gas may contain at least one of C 3 H 2 F 4 or C 4 H 2 F 6 . Each of C 3 H 2 F 4 and C 4 H 2 F 6 contains one double bond and one trifluoromethyl group.
- the first process gas may contain a C 3 F 6 gas as the C v1 F w1 gas and a C 3 H 2 F 4 gas as the C x2 H y2 F z2 gas.
- a ratio RT 1 of the flow rate of the C v1 F w1 gas to the flow rate of the C x2 H y2 F z2 gas may be 1 or more and 2 or less.
- the first process gas may further contain an oxygen-containing gas.
- the oxygen-containing gas may contain at least one of a CO gas, a COS gas, or an O 2 gas.
- the first process gas may further contain an inert gas.
- the inert gas may contain at least one of a noble gas such as Ar or a N 2 gas.
- the first plasma may be generated at a first pressure.
- the first pressure may be the pressure in the plasma processing chamber 10 .
- a first radio frequency power may be supplied to generate the first plasma.
- the first radio frequency power may be an RF power HF applied to an upper electrode of the plasma processing apparatus 1 .
- bias power LF may be applied to electrodes in a body 111 of the substrate support 11 .
- the bias power LF may be 10 kW or more.
- both the RF power HF and the bias power LF may be supplied periodically.
- the period during which the RF power HF is supplied may be synchronized with the period during which the bias power LF is supplied.
- the frequency for defining the period during which the RF power HF is supplied may be 1 kHz or greater and 10 kHz or smaller, or may be 1 kHz or greater and 5 kHz or smaller.
- the Duty ratio indicating the ratio of the supply time of the RF power HF within one period may be 10% or more and 90% or less, 20% or more and 80% or less, or 30% or more and 80% or less.
- the processing time of Step ST 2 may be 10 seconds or greater and 100 seconds or smaller.
- Step ST 2 may be performed as follows. First, a gas supply 20 supplies the first process gas into the plasma processing chamber 10 . Then, a plasma generator 12 generates the first plasma from the first process gas in the plasma processing chamber 10 . The controller 2 controls the gas supply 20 and the plasma generator 12 to etch the substrate W with the first plasma.
- Step ST 3 the substrate W is etched with a second plasma generated from the second process gas different from the first process gas.
- the second process gas may contain the same type of gas as the first process gas. In this case, the flow rate of at least one gas contained in the second process gas is different from the flow rate of at least one gas contained in the first process gas.
- the second process gas contains a C x1 H y1 F z1 (x1 is an integer of 2 or more, y1 and z1 are integers of 1 or more) gas containing an unsaturated bond.
- An example of the C x1 H y1 F z1 gas may be the same as an example of the C x2 H y2 F z2 gas.
- the second process gas may further contain a C v2 F w2 (v2 is an integer of 2 or more, and w2 is an integer of 1 or more) gas containing an unsaturated bond.
- a C v2 F w2 (v2 is an integer of 2 or more, and w2 is an integer of 1 or more) gas containing an unsaturated bond.
- An example of the C v2 F w2 gas may be the same as the example of the C v1 F w1 gas.
- the second process gas may contain a C 3 F 6 gas as the C v2 F w2 gas and a C 3 H 2 F 4 gas as the C x1 H y1 F z1 gas.
- a ratio RT 2 of the flow rate of the C v2 F w2 gas to the flow rate of the C x1 H y1 F z1 gas may be less than 1.
- the ratio RT 1 of the flow rate in Step ST 2 may be more than the ratio RT 2 of the flow rate in Step ST 3 .
- the flow rate of the C v2 F w2 gas in Step ST 3 may be less than the flow rate of the C v1 F w1 gas in Step ST 2 .
- the flow rate of the C x1 H y1 F z1 gas in Step ST 3 may be more than the flow rate of the C x2 H y2 F z2 gas in Step ST 3 .
- the second process gas may further contain an oxygen-containing gas.
- An example of the oxygen-containing gas contained in the second process gas may be the same as an example of the oxygen-containing gas contained in the first process gas.
- the second process gas may further contain an inert gas.
- An example of the inert gas contained in the second process gas may be the same as an example of the inert gas contained in the first process gas.
- the second plasma may be generated at a second pressure.
- the second pressure may be the pressure in the plasma processing chamber 10 .
- the first pressure in the plasma processing chamber 10 in Step ST 2 may be greater than the second pressure inside the plasma processing chamber 10 in Step ST 3 .
- a second radio frequency power may be supplied to generate the second plasma.
- the second radio frequency power may be an RF power HF applied to an upper electrode of the plasma processing apparatus 1 .
- bias power LF may be applied to electrodes in a body 111 of the substrate support 11 .
- the bias power LF may be 10 kW or more.
- both the RF power HF and the bias power LF may be supplied periodically.
- the period during which the RF power HF is supplied may be synchronized with the period during which the bias power LF is supplied.
- the range of the frequency for defining the period of supplying the RF power HF in Step ST 3 may be the same as the range of the frequency for defining the period of supplying the RF power HF in Step ST 2 .
- the range of the Duty ratio indicating the ratio of the supply time of the RF power HF within one period in Step ST 3 may be the same as the range of the Duty ratio indicating the ratio of the supply time of the RF power HF within one period in Step ST 2 .
- the processing time of Step ST 3 may be 5 seconds or greater and 50 seconds or smaller.
- the processing time of Step ST 2 may be longer than the processing time of Step ST 3 .
- the ratio of the processing time of Step ST 2 to the processing time of Step ST 3 may be more than 1 and 3 or less.
- Step ST 3 may be performed as follows. First, the gas supply 20 supplies the second process gas into the plasma processing chamber 10 . Then, the plasma generator 12 generates the second plasma from the second process gas in the plasma processing chamber 10 . The controller 2 controls the gas supply 20 and the plasma generator 12 to etch the substrate W with the second plasma.
- Step ST 4 Step ST 2 and Step ST 3 are repeated alternately. Step ST 4 may be ended when the number of times of performing each of Steps ST 2 and ST 3 reaches a threshold value.
- a recess RS 1 is formed in the first region R 1
- a recess RS 2 is formed in the second region R 2 .
- Each of the bottom of the recess RS 1 and the bottom of the recess RS 2 may reach the underlying region UR.
- Each of the recesses RS 1 and RS 2 may be a contact hole or a trench.
- the aspect ratio of the recess RS 1 and the aspect ratio of the recess RS 2 may be equal to or more than 10.
- an aspect ratio ASP 1 of the recess RS 1 is calculated by Expression (1) as follows.
- NCD in Expression (1) represents the minimum dimension of the opening OP 1 , as illustrated in FIG. 6 .
- the opening OP 1 has the minimum dimension at the neck of the mask MK.
- NHD in Expression (1) represents the distance from the position at which the opening OP 1 has the minimum dimension to the bottom of the recess RS 1 in the direction perpendicular to the main surface of the substrate W, as illustrated in FIG. 6 .
- An aspect ratio ASP 2 of the recess RS 2 is also calculated by the same expression as the aspect ratio ASP 1 of the recess RS 1 .
- Steps ST 2 and ST 3 higher-order radicals are generated from unsaturated bonds contained in the first process gas and the second process gas, respectively. Since the higher-order radicals have high molecular weights, so the higher-order radicals tend to form a deposited film on the surface of the mask MK. Since the mask MK is protected by the deposited film, it is possible to improve the etching selectivity of the first region R 1 and the second region R 2 with respect to the mask MK.
- the mechanism is considered as follows, the mechanism is not limited to this.
- the amount of radicals per unit flow rate, which are generated from the C v1 F w1 gas and the C x1 H y1 F z1 gas is more than the amount of radicals per unit flow rate, which are generated from a gas that does not contain the unsaturated bonds such as CH 2 F 2 gas.
- the hydrofluorocarbon gas can more effectively suppress the bowing of the side wall of the recess RS 2 than the bowing of the side wall of the recess RS 1 .
- Step ST 2 radicals generated from the C v1 F w1 gas go into the recesses RS 1 and RS 2 to form protective films on the side walls of the recesses RS 1 and RS 2 .
- the thickness of the protective film formed on the side wall of the recess RS 1 is more than the thickness of the protective film formed on the side wall of the recess RS 2 .
- Step ST 3 radicals generated from the C x1 H y1 F z1 gas go into the recesses RS 1 and RS 2 to form protective films on the side walls of the recesses RS 1 and RS 2 .
- the thickness of the protective film formed on the side wall of the recess RS 2 is more than the thickness of the protective film formed on the side wall of the recess RS 1 .
- Step ST 2 when the C v1 F w1 gas (for example, C 3 F 6 gas) is used in Step ST 2 , the openings OP 1 and OP 2 of the mask MK are less likely to be closed. As a result, the amount of radicals transported into the recesses RS 1 and RS 2 increases.
- C v1 F w1 gas for example, C 3 F 6 gas
- the second region R 2 can be preferentially etched over the first region R 1 in the Step ST 2 .
- fluorocarbon has an etching rate with respect to a silicon oxide film, which is higher than an etching rate with respect to a silicon nitride film.
- the first region R 1 can be preferentially etched over the second region R 2 . This is because hydrofluorocarbon has an etching rate with respect to a silicon nitride film, which is higher than an etching rate with respect to a silicon oxide film.
- Step ST 4 it is possible to increase the depth of the recess RS 1 and the depth of the recess RS 2 .
- a substrate W was on the substrate support 11 of the plasma processing chamber 10 in the plasma processing apparatus 1 (Step ST 1 ).
- the substrate W has the structure illustrated in FIG. 4 .
- a mask MK contains amorphous carbon.
- the substrate W was etched with first plasma generated from a first process gas that contains a C 3 F 6 gas containing a carbon double bond, a C 3 H 2 F 4 gas containing a carbon double bond, and an O 2 gas (Step ST 2 ).
- the ratio RT 1 of the flow rate of C 3 F 6 gas to the flow rate of the C 3 H 2 F 4 gas in Step ST 2 was 1.01.
- the substrate W was etched with second plasma generated from a second process gas that contains a C 3 F 6 gas containing a carbon double bond, a C 3 H 2 F 4 gas containing a carbon double bond, and an O 2 gas (Step ST 3 ).
- the ratio RT 2 of the flow rate of the C 3 F 6 gas to the flow rate of the C 3 H 2 F 4 gas in Step ST 3 was 0.98.
- the pressure in the plasma processing chamber 10 in Step ST 3 is lower than the pressure in the plasma processing chamber 10 in Step ST 2 .
- the processing time of Step ST 3 is shorter than the processing time of Step ST 2 .
- the ratio of the processing time of Step ST 2 to the processing time of Step ST 3 was 2.
- Step ST 2 and Step ST 3 were repeated alternately (Step ST 4 ).
- Step ST 2 and Step ST 3 were repeated alternately (Step ST 4 ).
- Step ST 4 a recess RS 1 was formed in the first region R 1
- a recess RS 2 was formed in the second region R 2 .
- Step ST 2 instead of the first process gas, a process gas containing a C 4 F 6 gas, a C 4 F 8 gas containing no unsaturated bond, a CH 2 F 2 gas, a krypton gas, and an O 2 gas was used.
- Step ST 3 instead of the second process gas, a process gas containing a C 4 F 6 gas, a C 4 F 8 gas containing no unsaturated bond, a CH 2 F 2 gas, a krypton gas, and an O 2 gas was used.
- the ratio of the total flow rate of the C 4 F 6 gas and the C 4 F 8 gas to the flow rate of the CH 2 F 2 gas in Step ST 2 was 1.0.
- the ratio of the total flow rate of the C 4 F 6 gas and the C 4 F 8 gas to the flow rate of the CH 2 F 2 gas in Step ST 3 was 1.0.
- the etching selectivity of the first region R 1 and the second region R 2 with respect to the mask MK was calculated.
- the etching selectivity is the etching amount of the first region R 1 or the second region R 2 with respect to the etching amount of the mask MK.
- the etching selectivity of the first region R 1 in the second experiment was 1, the etching selectivity of the first region R 1 in the first experiment was 4.89.
- the etching selectivity of the second region R 2 in the second experiment was 1, the etching selectivity of the second region R 2 in the first experiment was 5.48. Therefore, the etching selectivity in the first experiment was improved as compared with the second experiment.
- the etching rates of the first region R 1 and the second region R 2 were calculated. Assuming that the etching rate of the first region R 1 in the second experiment was 1, the etching rate of the first region R 1 in the first experiment was 1.09. Assuming that the etching rate of the second region R 2 in the second experiment was 1, the etching rate of the second region R 2 in the first experiment was 1.09. Therefore, the etching rate in the first experiment was improved as compared with the second experiment.
- the dimensions of the recesses RS 1 and RS 2 are increased in parts of the side walls of the recess RS 1 and the recess RS 2 .
- the maximum value of each of the dimensions of the recesses RS 1 and RS 2 was set as the bowing dimension.
- a ratio B/D of the bowing dimension to the depths of the recesses RS 1 and RS 2 was calculated for the recesses RS 1 and RS 2 . Assuming that the ratio B/D of the recess RS 1 in the second experiment was 1, the ratio B/D of the recess RS 1 in the first experiment was 0.95.
- Etching conditions were selected so that the bowing dimension of the recess RS 1 in the second experiment was substantially the same as the bowing dimension of the recess RS 1 in the first experiment. Assuming that the bowing dimension of the recess RS 1 in the second experiment was 1, the bowing dimension of the recess RS 2 in the second experiment was 1.51, and the bowing dimension of the recess RS 2 in the first experiment was 1.40. Therefore, in the first experiment, it is possible to suppress not only the bowing of the side wall of the recess RS 1 but also to greatly suppress the bowing of the side wall of the recess RS 2 .
- the openings OP 1 and OP 2 of the mask MK are less likely to be closed in Steps ST 2 and ST 3 , as compared with the second experiment. Therefore, when Steps ST 2 and ST 3 are repeated alternately in Step ST 4 , the effect of increasing the etching rate and the effect of suppressing the bowing, as described above, are significantly enhanced.
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Condensed Matter Physics & Semiconductors (AREA)
- Manufacturing & Machinery (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Power Engineering (AREA)
- Chemical Kinetics & Catalysis (AREA)
- General Chemical & Material Sciences (AREA)
- Inorganic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Plasma & Fusion (AREA)
- Drying Of Semiconductors (AREA)
Abstract
An etching method includes (a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask; (b) etching the substrate with a first plasma generated from a first process gas; and (c) etching the substrate with a second plasma generated from a second process gas different from the first process gas. The first process gas contains a Cv1Fw1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond. The second process gas contains a Cx1Hy1Fz1 (x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more) gas containing an unsaturated bond.
Description
- This application is based on and claims the benefit of priority from Japanese Patent Application No. 2022-082922 filed on May 20, 2022, the entire contents of which are incorporated herein by reference.
- Exemplary embodiments of the present disclosure relate to an etching method and a plasma processing apparatus.
- Japanese Unexamined Patent Publication No. 2016-51750 discloses a method of etching a first region having a multilayer film formed by alternately providing a silicon oxide film and a silicon nitride film and a second region having a single-layer silicon oxide film. According to the etching method disclosed in Japanese Unexamined Patent Publication No. 2016-51750, a step of generating a plasma of a first process gas containing hydrofluorocarbon and a step of generating a plasma of a second process gas containing fluorocarbon are repeated alternately.
- In an exemplary embodiment, an etching method includes (a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask on the first region and the second region; (b) etching the substrate with a first plasma generated from a first process gas; and (c) etching the substrate with a second plasma generated from a second process gas different from the first process gas, wherein the first process gas contains a Cv1Fw1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond, and the second process gas contains a Cx1Hy1Fz1 (x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more) gas containing an unsaturated bond.
- The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, exemplary embodiments, and features described above, further aspects, exemplary embodiments, and features will become apparent by reference to the drawings and the following detailed description.
-
FIG. 1 is a schematic diagram illustrating a plasma processing apparatus according to an exemplary embodiment. -
FIG. 2 is a schematic diagram illustrating the plasma processing apparatus according to an exemplary embodiment. -
FIG. 3 is a flowchart illustrating an etching method according to an exemplary embodiment. -
FIG. 4 is a cross-sectional view of an example substrate to which the method ofFIG. 3 can be applied. -
FIG. 5 is a cross-sectional view of an example substrate after the method ofFIG. 3 has been applied. -
FIG. 6 is a cross-sectional view of a substrate having a recess having an example aspect ratio. - Hereinafter, various exemplary embodiments (1) to (18) will be described.
- (1) An etching method includes (a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask on the first region and the second region; (b) etching the substrate with a first plasma generated from a first process gas; and (c) etching the substrate with a second plasma generated from a second process gas different from the first process gas, wherein the first process gas contains a Cv1Fw1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond, and the second process gas contains a Cx1Hy1Fz1 (x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more) gas containing an unsaturated bond.
- According to the above etching method, it is possible to improve etching selectivity of the first region and the second region with respect to the mask. Although the mechanism is considered as follows, the mechanism is not limited to this. In (b) and (c), higher-order radicals are generated from unsaturated bonds contained in the first process gas and the second process gas, respectively. Higher-order radicals have high molecular weights, so the higher-order radicals tend to form a deposited film on the surface of the mask. As a result, it is possible to improve the etching selectivity of the first region and the second region with respect to the mask.
- (2) In the above (1), the etching method may further include (d) repeating (b) and (c) alternately. In this case, it is possible to increase the depth of a recess formed in the first region and the depth of a recess formed in the second region.
- (3) In the above (1) or (2), the first process gas may further contain a Cx2Hy2Fz2 (x2 is an integer of 2 or more, and y2 and z2 are integers of 1 or more) gas containing an unsaturated bond, and the second process gas may further contain a Cv2Fw2 (v2 is an integer of 2 or more, and w2 is an integer of 1 or more) gas containing an unsaturated bond, and a ratio of a flow rate of the Cv1Fw1 gas to a flow rate of the Cx2Hy2Fz2 gas may be greater than a ratio of a flow rate of the Cv2Fw2 gas to a flow rate of the Cx1Hy1Fz1 gas.
- A fluorocarbon gas has an etching rate with respect to a silicon oxide film, which is higher than an etching rate with respect to a silicon nitride film. Hydrofluorocarbon has an etching rate with respect to the silicon nitride film, which is higher than an etching rate with respect to the silicon oxide film. Thus, in (b), the second region is preferentially etched over the first region. In (c), the first region is preferentially etched over the second region.
- (4) In the above (3), the ratio of the flow rate of the Cv1Fw1 gas to the flow rate of the Cx2Hy2Fz2 gas may be 1 or more and 2 or less.
- (5) In the above (3) or (4), the ratio of the flow rate of the Cv2Fw2 gas to the flow rate of the Cx1Hy1Fz1 gas may be less than 1.
- (6) In any one of the above (1) to (5), the Cv1Fw1 gas may contain a fluoromethyl group. In this case, in (b), a lower-order radical is generated from the fluoromethyl group. Since the lower-order radicals have low molecular weights, the lower-order radicals can go deep into a recess formed by etching. Thus, it is possible to form a deep recess by etching.
- (7) In the above (6), the Cv1Fw1 gas may contain at least one of C4F8 or C3F6.
- (8) In any one of the above (1) to (7), the Cx1Hy1Fz1 gas may contain a fluoromethyl group. In this case, in (c), lower-order radicals are generated from the fluoromethyl group. Since the lower-order radicals have low molecular weights, the lower-order radicals can go deep into a recess formed by etching. Thus, it is possible to form a deep recess by etching.
- (9) In the above (8), the Cx1Hy1Fz1 gas may contain at least one of C3H2F4 or C4H2F6.
- (10) In any one of the above (1) to (7), the Cv1Fw1 gas may contain C3F6, and the Cx1Hy1Fz1 gas may contain C3H2F4.
- (11) In any one of the above (1) to (10), a pressure in the chamber in (b) may be higher than a pressure in the chamber in (c).
- (12) In any one of the above (1) to (11), a processing time of (b) may be longer than a processing time of (c).
- (13) In the above (12), a ratio of the processing time of (b) to the processing time of (c) may be more than 1 and 3 or less.
- (14) In any one of the above (1) to (13), wherein an aspect ratio of a recess formed in the first region and an aspect ratio of a recess formed in the second region in the substrate after the etching method has been applied may be equal to or more than 10.
- (15) In any one of the above (1) to (14), at least one of the first process gas or the second process gas may further contain an oxygen-containing gas.
- (16) In any one of the above (1) to (15), wherein at least one of the first process gas or the second process gas may further contain an inert gas.
- (17) In any one of the above (1) to (16), the mask may contain at least one of carbon or boron.
- (18) A plasma processing apparatus includes a chamber; a substrate support for supporting a substrate in the chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask on the first region and the second region; a gas supply configured to supply a first process gas and a second process gas different from the first process gas into the chamber; a plasma generator configured to generate a first plasma and a second plasma from the first process gas and the second process gas in the chamber, respectively; and a controller, wherein the first process gas contains a Cv1Fw1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond, the second process gas contains a Cx1Hy1Fz1 (x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more) gas containing an unsaturated bond, and the controller is configured to control the gas supply and the plasma generator to etch the substrate with the first plasma, and etch the substrate with the second plasma.
- Hereinafter, various exemplary embodiments will be described in detail with reference to the drawings. In the drawing, the same or equivalent portions are denoted by the same reference symbols.
-
FIG. 1 illustrates an example configuration of a plasma processing system. In an embodiment, the plasma processing system includes aplasma processing apparatus 1 and acontroller 2. The plasma processing system is an example substrate processing system, and theplasma processing apparatus 1 is an example substrate processing apparatus. Theplasma processing apparatus 1 includes aplasma processing chamber 10, asubstrate support 11, and aplasma generator 12. Theplasma processing chamber 10 has a plasma processing space. Theplasma processing chamber 10 further has at least one gas inlet for supplying at least one process gas into the plasma processing space and at least one gas outlet for exhausting gases from the plasma processing space. The gas inlet is connected to a gas supply 20 described below and the gas outlet is connected to a gas exhaust system 40 described below. Thesubstrate support 11 is disposed in a plasma processing space and has a substrate supporting surface for supporting a substrate. - The
plasma generator 12 is configured to generate a plasma from the at least one process gas supplied into the plasma processing space. The plasma formed in the plasma processing space may be, for example, a capacitively coupled plasma (CCP), an inductively coupled plasma (ICP), an electron-cyclotron-resonance (ECR) plasma, a helicon wave plasma (HWP), or a surface wave plasma (SWP). Various types of plasma generators may also be used, such as an alternating current (AC) plasma generator and a direct current (DC) plasma generator. In an embodiment, AC signal (AC power) used in the AC plasma generator has a frequency in a range of 100 kHz to 10 GHz. Hence, examples of the AC signal include a radio frequency (RF) signal and a microwave signal. In an embodiment, the RF signal has a frequency in a range of 100 kHz to 150 MHz. - The
controller 2 processes computer executable instructions causing theplasma processing apparatus 1 to perform various steps described in this disclosure. Thecontroller 2 may be configured to control individual components of theplasma processing apparatus 1 such that these components execute the various steps. In an embodiment, the functions of thecontroller 2 may be partially or entirely incorporated into theplasma processing apparatus 1. Thecontroller 2 may include aprocessor 2 a 1, astorage 2 a 2, and acommunication interface 2 a 3. Thecontroller 2 is implemented in, for example, acomputer 2 a. Theprocessor 2 a 1 may be configured to read a program from thestorage 2 a 2, and then perform various controlling operations by executing the program. This program may be preliminarily stored in thestorage 2 a 2 or retrieved from any medium, as appropriate. The resulting program is stored in thestorage 2 a 2, and then theprocessor 2 a 1 reads to execute the program from thestorage 2 a 2. The medium may be of any type which can be accessed by thecomputer 2 a or may be a communication line connected to thecommunication interface 2 a 3. Theprocessor 2 a 1 may be a central processing unit (CPU). Thestorage 2 a 2 may include a random access memory (RAM), a read only memory (ROM), a hard disk drive (HDD), a solid state drive (SSD), or any combination thereof. Thecommunication interface 2 a 3 can communicate with theplasma processing apparatus 1 via a communication line, such as a local area network (LAN). - An example configuration of a capacitively coupled plasma processing apparatus, which is an example of the
plasma processing apparatus 1, will now be described.FIG. 2 illustrates the example configuration of the capacitively coupled plasma processing apparatus. - The capacitively coupled
plasma processing apparatus 1 includes aplasma processing chamber 10, a gas supply 20, an electric power source 30, and a gas exhaust system 40. Theplasma processing apparatus 1 further includes asubstrate support 11 and a gas introduction unit. The gas introduction unit is configured to introduce at least one process gas into theplasma processing chamber 10. The gas introduction unit includes ashowerhead 13. Thesubstrate support 11 is disposed in aplasma processing chamber 10. Theshowerhead 13 is disposed above thesubstrate support 11. In an embodiment, theshowerhead 13 functions as at least part of the ceiling of theplasma processing chamber 10. Theplasma processing chamber 10 has aplasma processing space 10 s that is defined by theshowerhead 13, the sidewall 10 a of theplasma processing chamber 10, and thesubstrate support 11. Theplasma processing chamber 10 is grounded. Theshowerhead 13 and thesubstrate support 11 are electrically insulated from the housing of theplasma processing chamber 10. - The
substrate support 11 includes a body 111 and aring assembly 112. The body 111 has a central region 111 a for supporting a substrate V and anannular region 111 b for supporting thering assembly 112. An example of the substrate W is a wafer. Theannular region 111 b of the body 111 surrounds the central region 111 a of the body 111 in plan view. The substrate W is disposed on the central region 111 a of the body 111, and thering assembly 112 is disposed on theannular region 111 b of the body 111 so as to surround the substrate W on the central region 111 a of the body 111. Thus, the central region 111 a is also called a substrate supporting surface for supporting the substrate W, while theannular region 111 b is also called a ring supporting surface for supporting thering assembly 112. - In an embodiment, the body 111 includes a base 1110 and an electrostatic chuck 1111. The base 1110 includes a conductive member. The conductive member of the base 1110 can function as a lower electrode. The electrostatic chuck 1111 is disposed on the base 1110. The electrostatic chuck 1111 includes a
ceramic member 1111 a and an electrostatic electrode 1111 b disposed in theceramic member 1111 a. Theceramic member 1111 a has the central region 111 a. In an embodiment, theceramic member 1111 a also has theannular region 111 b. Any other member, such as an annular electrostatic chuck or an annular insulting member, surrounding the electrostatic chuck 1111 may have theannular region 111 b. In this case, thering assembly 112 may be disposed on either the annular electrostatic chuck or the annular insulating member, or both the electrostatic chuck 1111 and the annular insulating member. At least one RF/DC electrode coupled to an RF source 31 and/or aDC source 32 described below may be disposed in theceramic member 1111 a. In this case, the at least one RF/DC electrode functions as the lower electrode. If a bias RF signal and/or DC signal described below are supplied to the at least one RF/DC electrode, the RF/DC electrode is also called a bias electrode. It is noted that the conductive member of the base 1110 and the at least one RF/DC electrode may each function as a lower electrode. The electrostatic electrode 1111 b may also be function as a lower electrode. Thesubstrate support 11 accordingly includes at least one lower electrode. - The
ring assembly 112 includes one or more annular members. In an embodiment, the annular members include one or more edge rings and at least one cover ring. The edge ring is composed of a conductive or insulating material, whereas the cover ring is composed of an insulating material. - The
substrate support 11 may also include a temperature adjusting module that is configured to adjust at least one of the electrostatic chuck 1111, thering assembly 112, and the substrate to a target temperature. The temperature adjusting module may be a heater, a heat transfer medium, aflow passage 1110 a, or any combination thereof. A heat transfer fluid, such as brine or gas, flows into theflow passage 1110 a. In an embodiment, theflow passage 1110 a is formed in the base 1110, one or more heaters are disposed in theceramic member 1111 a of the electrostatic chuck 1111. Thesubstrate support 11 may further include a heat transfer gas supply configured to supply a heat transfer gas to a gap between the rear surface of the substrate W and the central region 111 a. - The
showerhead 13 is configured to introduce at least one process gas from the gas supply 20 into theplasma processing space 10 s. Theshowerhead 13 has at least onegas inlet 13 a, at least one gas diffusing space 13 b, and a plurality of gas feeding ports 13 c. The process gas supplied to thegas inlet 13 a passes through the gas diffusing space 13 b and is then introduced into theplasma processing space 10 s from the gas feeding ports 13 c. Theshowerhead 13 further includes at least one upper electrode. The gas introduction unit may include one or more side gas injectors provided at one or more openings formed in the sidewall 10 a, in addition to theshowerhead 13. - The gas supply 20 may include at least one gas source 21 and at least one
flow controller 22. In an embodiment, the gas supply 20 is configured to supply at least one process gas from the corresponding gas source 21 through thecorresponding flow controller 22 into theshowerhead 13. Eachflow controller 22 may be, for example, a mass flow controller or a pressure-controlled flow controller. The gas supply 20 may include a flow modulation device that can modulate or pulse the flow of the at least one process gas. - The electric power source 30 include an RF source 31 coupled to the
plasma processing chamber 10 through at least one impedance matching circuit. The RF source 31 is configured to supply at least one RF signal (RF power) to at least one lower electrode and/or at least one upper electrode. A plasma is thereby formed from at least one process gas supplied into theplasma processing space 10 s. Thus, the RF source 31 can function as at least part of theplasma generator 12. The bias RF signal supplied to the at least one lower electrode causes a bias potential to occur in the substrate W, which potential then attracts ionic components in the plasma to the substrate W. - In an embodiment, the RF source 31 includes a
first RF generator 31 a and a second RF generator 31 b. Thefirst RF generator 31 a is coupled to the at least one lower electrode and/or the at least one upper electrode through the at least one impedance matching circuit and is configured to generate a source RF signal (source RF power) for generating a plasma. In an embodiment, the source RF signal has a frequency in a range of 10 MHz to 150 MHz. In an embodiment, thefirst RF generator 31 a may be configured to generate two or more source RF signals having different frequencies. The resulting source RF signal(s) is supplied to the at least one lower electrode and/or the at least one upper electrode. - The second RF generator 31 b is coupled to the at least one lower electrode through the at least one impedance matching circuit and is configured to generate a bias RF signal (bias RF power). The bias RF signal and the source RF signal may have the same frequency or different frequencies. In an embodiment, the bias RF signal has a frequency which is less than that of the source RF signal. In an embodiment, the bias RF signal has a frequency in a range of 100 kHz to 60 MHz. In an embodiment, the second RF generator 31 b may be configured to generate two or more bias RF signals having different frequencies. The resulting bias RF signal(s) is supplied to the at least one lower electrode. In various embodiments, at least one of the source RF signal and the bias RF signal may be pulsed.
- The electric power source 30 may also include a
DC source 32 coupled to theplasma processing chamber 10. TheDC source 32 includes afirst DC generator 32 a and asecond DC generator 32 b. In an embodiment, thefirst DC generator 32 a is connected to the at least one lower electrode and is configured to generate a first DC signal. The resulting first DC signal is applied to the at least one lower electrode. In an embodiment, thesecond DC generator 32 b is connected to the at least one upper electrode and is configured to generate a second DC signal. The resulting second DC signal is applied to the at least one upper electrode. - In various embodiments, the first and second DC signals may be pulsed. In this case, a sequence of voltage pulses is applied to the at least one lower electrode and/or the at least one upper electrode. The voltage pulses have rectangular, trapezoidal, or triangular waveform, or a combined waveform thereof. In an embodiment, a waveform generator for generating a sequence of voltage pulses from the DC signal is disposed between the
first DC generator 32 a and the at least one lower electrode. Thefirst DC generator 32 a and the waveform generator thereby functions as a voltage pulse generator. In the case that thesecond DC generator 32 b and the waveform generator functions as a voltage pulse generator, the voltage pulse generator is connected to the at least one upper electrode. The voltage pulse may have positive polarity or negative polarity. A sequence of voltage pulses may also include one or more positive voltage pulses and one or more negative voltage pulses in a cycle. The first andsecond DC generators first DC generator 32 a may be disposed in place of the second RF generator 31 b. - The gas exhaust system 40 may be connected to, for example, a gas outlet 10 e provided in the bottom wall of the
plasma processing chamber 10. The gas exhaust system 40 may include a pressure regulation valve and a vacuum pump. The pressure regulation valve enables the pressure in theplasma processing space 10 s to be adjusted. The vacuum pump may be a turbo-molecular pump, a dry pump, or a combination thereof. -
FIG. 3 is a flowchart illustrating an etching method according to an exemplary embodiment. An etching method MT (referred to as a “method MT” below) illustrated inFIG. 3 can be performed by theplasma processing apparatus 1 in the above embodiment. The method MT can be applied to a substrate W. -
FIG. 4 is a cross-sectional view of an example substrate to which the method ofFIG. 3 can be applied. As illustrated inFIG. 4 , in the embodiment, the substrate W includes a first region R1, a second region R2, and a mask MK. The mask MK is on the first region R1 and the second region R2. The substrate W may include an underlying region UR. The first region R1 and the second region R2 may be provided on the underlying region UR. - The first region R1 has a multilayer film in which silicon oxide films L1 and silicon nitride films L2 are alternately stacked. The silicon oxide film L1 may be located on each of the top surface and the bottom surface of the first region R1. The second region R2 has a single-layer silicon oxide film. The first region R1 and the second region R2 may be arranged in a direction along the main surface of the substrate W. In a direction perpendicular to the main surface of the substrate W, the first region R1 may have the same thickness as the second region R2. Each of the first region R1 and the second region R2 may be a film for a memory device such as a 3D-NAND.
- The mask MK may have an opening OP1 over the first region R1 and an opening OP2 over the second region R2. The mask MK may contain at least one of carbon or boron. The mask MK may contain at least one of spin-on carbon, tungsten carbide, or amorphous carbon. The mask MK may contain at least one of boron nitride or boron carbide.
- The underlying region UR may contain at least one of silicon, organic (carbon-containing) material, or metal.
- The method MT will be described with reference to
FIGS. 3 to 5 by using, as an example, the case where the method MT is applied to the substrate W by using theplasma processing apparatus 1 in the above-described embodiment.FIG. 5 is a cross-sectional view of an example substrate after the method ofFIG. 3 has been applied. When theplasma processing apparatus 1 is used, the method MT can be performed in theplasma processing apparatus 1 in a manner that thecontroller 2 controls each unit of theplasma processing apparatus 1. In the method MT, as illustrated inFIG. 2 , the substrate W on asubstrate support 11 disposed in aplasma processing chamber 10 is processed. - As illustrated in
FIG. 3 , the method MT can include Steps ST1 to ST4. Steps ST1 to ST4 can be performed in order. The method MT may not include Step ST4. Step ST3 may be performed before Step ST2. - In Step ST1, the substrate W illustrated in
FIG. 4 is on thesubstrate support 11 in theplasma processing chamber 10. The underlying region UR can be disposed between the first region R1 or the second region R2, and thesubstrate support 11. - In Step ST2, the substrate W is etched with a first plasma generated from a first process gas. By etching the first region R1, a recess corresponding to the opening OP1 of the mask MK can be formed in the first region R1. By etching the second region R2, a recess corresponding to the opening OP2 of the mask MK can be formed in the second region R2.
- The first process gas contains a Cv1Fw1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond. The Cv1Fw1 gas is a fluorocarbon gas. The unsaturated bond may include a carbon double bond or a carbon triple bond. The Cv1Fw1 gas may contain a plurality of unsaturated bonds. The Cv1Fw1 gas may contain a fluorine substituent. The Cv1Fw1 gas may contain a fluoromethyl group (—CFx). The Cv1Fw1 gas may contain a plurality of fluoromethyl groups. The fluoromethyl group may be a monofluoromethyl group, a difluoromethyl group, or a trifluoromethyl group. The Cv1Fw1 gas may contain at least one of C4F8 or C3F6. Each of C4F8 and C3F6 contains one double bond and one trifluoromethyl group.
- The first process gas may further contain a Cx2Hy2Fz2 (x2 is an integer of 2 or more, and y2 and z2 are integers of 1 or more) gas containing an unsaturated bond. The Cx2Hy2Fz2 gas is a hydrofluorocarbon gas. The unsaturated bond may include a carbon double bond or a carbon triple bond. The Cx2Hy2Fz2 gas may contain a plurality of unsaturated bonds. The Cx2Hy2Fz2 gas may contain a fluorine substituent. The Cx2Hy2Fz2 gas may contain a fluoromethyl group (—CFx). The Cx2Hy2Fz2 gas may contain a plurality of fluoromethyl groups. The fluoromethyl group may be a monofluoromethyl group, a difluoromethyl group, or a trifluoromethyl group. The Cx2Hy2Fz2 gas may contain at least one of C3H2F4 or C4H2F6. Each of C3H2F4 and C4H2F6 contains one double bond and one trifluoromethyl group.
- The first process gas may contain a C3F6 gas as the Cv1Fw1 gas and a C3H2F4 gas as the Cx2Hy2Fz2 gas. A ratio RT1 of the flow rate of the Cv1Fw1 gas to the flow rate of the Cx2Hy2Fz2 gas may be 1 or more and 2 or less.
- The first process gas may further contain an oxygen-containing gas. The oxygen-containing gas may contain at least one of a CO gas, a COS gas, or an O2 gas. The first process gas may further contain an inert gas. The inert gas may contain at least one of a noble gas such as Ar or a N2 gas.
- The first plasma may be generated at a first pressure. The first pressure may be the pressure in the
plasma processing chamber 10. A first radio frequency power may be supplied to generate the first plasma. The first radio frequency power may be an RF power HF applied to an upper electrode of theplasma processing apparatus 1. In Step ST2, bias power LF may be applied to electrodes in a body 111 of thesubstrate support 11. The bias power LF may be 10 kW or more. - In Step ST2, both the RF power HF and the bias power LF may be supplied periodically. The period during which the RF power HF is supplied may be synchronized with the period during which the bias power LF is supplied. The frequency for defining the period during which the RF power HF is supplied may be 1 kHz or greater and 10 kHz or smaller, or may be 1 kHz or greater and 5 kHz or smaller. In this case, the Duty ratio indicating the ratio of the supply time of the RF power HF within one period may be 10% or more and 90% or less, 20% or more and 80% or less, or 30% or more and 80% or less. By controlling the frequency and the Duty ratio of the RF power HF within the above range, it is possible to suppress plasma dissociation and increase the generated amount of higher-order radicals.
- The processing time of Step ST2 may be 10 seconds or greater and 100 seconds or smaller.
- Step ST2 may be performed as follows. First, a gas supply 20 supplies the first process gas into the
plasma processing chamber 10. Then, aplasma generator 12 generates the first plasma from the first process gas in theplasma processing chamber 10. Thecontroller 2 controls the gas supply 20 and theplasma generator 12 to etch the substrate W with the first plasma. - In Step ST3, the substrate W is etched with a second plasma generated from the second process gas different from the first process gas. The second process gas may contain the same type of gas as the first process gas. In this case, the flow rate of at least one gas contained in the second process gas is different from the flow rate of at least one gas contained in the first process gas. By etching the first region R1, a recess corresponding to the opening OP1 of the mask MK can be formed in the first region R1. By etching the second region R2, a recess corresponding to the opening OP2 of the mask MK can be formed in the second region R2.
- The second process gas contains a Cx1Hy1Fz1 (x1 is an integer of 2 or more, y1 and z1 are integers of 1 or more) gas containing an unsaturated bond. An example of the Cx1Hy1Fz1 gas may be the same as an example of the Cx2Hy2Fz2 gas.
- The second process gas may further contain a Cv2Fw2 (v2 is an integer of 2 or more, and w2 is an integer of 1 or more) gas containing an unsaturated bond. An example of the Cv2Fw2 gas may be the same as the example of the Cv1Fw1 gas.
- The second process gas may contain a C3F6 gas as the Cv2Fw2 gas and a C3H2F4 gas as the Cx1Hy1Fz1 gas. A ratio RT2 of the flow rate of the Cv2Fw2 gas to the flow rate of the Cx1Hy1Fz1 gas may be less than 1. The ratio RT1 of the flow rate in Step ST2 may be more than the ratio RT2 of the flow rate in Step ST3. The flow rate of the Cv2Fw2 gas in Step ST3 may be less than the flow rate of the Cv1Fw1 gas in Step ST2. The flow rate of the Cx1Hy1Fz1 gas in Step ST3 may be more than the flow rate of the Cx2Hy2Fz2 gas in Step ST3.
- The second process gas may further contain an oxygen-containing gas. An example of the oxygen-containing gas contained in the second process gas may be the same as an example of the oxygen-containing gas contained in the first process gas. The second process gas may further contain an inert gas. An example of the inert gas contained in the second process gas may be the same as an example of the inert gas contained in the first process gas.
- The second plasma may be generated at a second pressure. The second pressure may be the pressure in the
plasma processing chamber 10. The first pressure in theplasma processing chamber 10 in Step ST2 may be greater than the second pressure inside theplasma processing chamber 10 in Step ST3. A second radio frequency power may be supplied to generate the second plasma. The second radio frequency power may be an RF power HF applied to an upper electrode of theplasma processing apparatus 1. In Step ST3, bias power LF may be applied to electrodes in a body 111 of thesubstrate support 11. The bias power LF may be 10 kW or more. - In Step ST3, both the RF power HF and the bias power LF may be supplied periodically. The period during which the RF power HF is supplied may be synchronized with the period during which the bias power LF is supplied. The range of the frequency for defining the period of supplying the RF power HF in Step ST3 may be the same as the range of the frequency for defining the period of supplying the RF power HF in Step ST2. In this case, the range of the Duty ratio indicating the ratio of the supply time of the RF power HF within one period in Step ST3 may be the same as the range of the Duty ratio indicating the ratio of the supply time of the RF power HF within one period in Step ST2.
- The processing time of Step ST3 may be 5 seconds or greater and 50 seconds or smaller. The processing time of Step ST2 may be longer than the processing time of Step ST3. The ratio of the processing time of Step ST2 to the processing time of Step ST3 may be more than 1 and 3 or less.
- Step ST3 may be performed as follows. First, the gas supply 20 supplies the second process gas into the
plasma processing chamber 10. Then, theplasma generator 12 generates the second plasma from the second process gas in theplasma processing chamber 10. Thecontroller 2 controls the gas supply 20 and theplasma generator 12 to etch the substrate W with the second plasma. - In Step ST4, Step ST2 and Step ST3 are repeated alternately. Step ST4 may be ended when the number of times of performing each of Steps ST2 and ST3 reaches a threshold value.
- In the substrate W after the method MT has been applied, as illustrated in
FIG. 5 , a recess RS1 is formed in the first region R1, and a recess RS2 is formed in the second region R2. Each of the bottom of the recess RS1 and the bottom of the recess RS2 may reach the underlying region UR. Each of the recesses RS1 and RS2 may be a contact hole or a trench. The aspect ratio of the recess RS1 and the aspect ratio of the recess RS2 may be equal to or more than 10. In the present disclosure, an aspect ratio ASP1 of the recess RS1 is calculated by Expression (1) as follows. -
ASP1=1000×NCD/NHD (1) - NCD in Expression (1) represents the minimum dimension of the opening OP1, as illustrated in
FIG. 6 . The opening OP1 has the minimum dimension at the neck of the mask MK. NHD in Expression (1) represents the distance from the position at which the opening OP1 has the minimum dimension to the bottom of the recess RS1 in the direction perpendicular to the main surface of the substrate W, as illustrated inFIG. 6 . Thus, the shallower the recess RS1, the more the aspect ratio ASP1. An aspect ratio ASP2 of the recess RS2 is also calculated by the same expression as the aspect ratio ASP1 of the recess RS1. - According to the method MT, it is possible to improve the etching selectivity of the first region R1 and the second region R2 with respect to the mask MK. Although the mechanism is considered as follows, the mechanism is not limited to this. In Steps ST2 and ST3, higher-order radicals are generated from unsaturated bonds contained in the first process gas and the second process gas, respectively. Since the higher-order radicals have high molecular weights, so the higher-order radicals tend to form a deposited film on the surface of the mask MK. Since the mask MK is protected by the deposited film, it is possible to improve the etching selectivity of the first region R1 and the second region R2 with respect to the mask MK.
- Furthermore, according to the method MT, it is possible to not only suppress bowing (abnormal shape) of the side wall of the recess RS1 formed in the first region R1, but also to greatly suppress bowing of the side wall of the recess RS2 formed in the second region R2. Although the mechanism is considered as follows, the mechanism is not limited to this. First, the amount of radicals per unit flow rate, which are generated from the Cv1Fw1 gas and the Cx1Hy1Fz1 gas, is more than the amount of radicals per unit flow rate, which are generated from a gas that does not contain the unsaturated bonds such as CH2F2 gas. Furthermore, the hydrofluorocarbon gas can more effectively suppress the bowing of the side wall of the recess RS2 than the bowing of the side wall of the recess RS1. In Step ST2, radicals generated from the Cv1Fw1 gas go into the recesses RS1 and RS2 to form protective films on the side walls of the recesses RS1 and RS2. When the Cv1Fw1 gas is used, the thickness of the protective film formed on the side wall of the recess RS1 is more than the thickness of the protective film formed on the side wall of the recess RS2. Thus, it is possible to suppress bowing of the side wall of the recess RS1. In Step ST3, radicals generated from the Cx1Hy1Fz1 gas go into the recesses RS1 and RS2 to form protective films on the side walls of the recesses RS1 and RS2. When the Cx1Hy1Fz1 gas is used, the thickness of the protective film formed on the side wall of the recess RS2 is more than the thickness of the protective film formed on the side wall of the recess RS1. Thus, it is possible to suppress bowing of the side wall of the recess RS2. Furthermore, when the Cv1Fw1 gas (for example, C3F6 gas) is used in Step ST2, the openings OP1 and OP2 of the mask MK are less likely to be closed. As a result, the amount of radicals transported into the recesses RS1 and RS2 increases.
- When the ratio RT1 of the flow rate in Step ST2 is more than the ratio RT2 of the flow rate in Step ST3, the second region R2 can be preferentially etched over the first region R1 in the Step ST2. This is because fluorocarbon has an etching rate with respect to a silicon oxide film, which is higher than an etching rate with respect to a silicon nitride film. In Step ST3, the first region R1 can be preferentially etched over the second region R2. This is because hydrofluorocarbon has an etching rate with respect to a silicon nitride film, which is higher than an etching rate with respect to a silicon oxide film. Thus, it is possible to control the depth of the recess RS1 formed in the first region R1 and the depth of the recess RS2 formed in the second region R2 independently of each other. Therefore, it is possible to reduce the difference between the depth of the recess RS1 and the depth of the recess RS2.
- When the method MT includes Step ST4, it is possible to increase the depth of the recess RS1 and the depth of the recess RS2.
- When the Cv1Fw1 gas contains a fluoromethyl group, lower-order radicals are generated from the fluoromethyl group in Step ST2. Similarly, when the Cx1Hy1Fz1 gas contains a fluoromethyl group, lower-order radicals are generated from the fluoromethyl group in Step ST3. Since the lower-order radicals have low molecular weights, the lower-order radicals can go deep into the recesses RS1 and RS2 formed by etching. Thus, it is possible to form the deep recesses RS1 and RS2. Further, since many lower-order radicals are supplied into the recesses RS1 and RS2, it is possible to increase the etching rate of the first region R1 and the second region R2. Furthermore, since a polymer film is less likely to be formed on the shoulders of the side walls of the recesses RS1 and RS2, it is possible to suppress the clogging of the recesses RS1 and RS2 by the polymer film.
- Although the various exemplary embodiments have been described above, various additions, omissions, substitutions, and changes may be made without being limited to the exemplary embodiments described above. Other embodiments can be formed by combining elements in different embodiments.
- Various experiments performed for evaluating the method MT are described below. The experiments described below do not limit the present disclosure.
- First Experiment
- In a first experiment, a substrate W was on the
substrate support 11 of theplasma processing chamber 10 in the plasma processing apparatus 1 (Step ST1). The substrate W has the structure illustrated inFIG. 4 . A mask MK contains amorphous carbon. - Then, the substrate W was etched with first plasma generated from a first process gas that contains a C3F6 gas containing a carbon double bond, a C3H2F4 gas containing a carbon double bond, and an O2 gas (Step ST2). The ratio RT1 of the flow rate of C3F6 gas to the flow rate of the C3H2F4 gas in Step ST2 was 1.01.
- Then, the substrate W was etched with second plasma generated from a second process gas that contains a C3F6 gas containing a carbon double bond, a C3H2F4 gas containing a carbon double bond, and an O2 gas (Step ST3). The ratio RT2 of the flow rate of the C3F6 gas to the flow rate of the C3H2F4 gas in Step ST3 was 0.98. The pressure in the
plasma processing chamber 10 in Step ST3 is lower than the pressure in theplasma processing chamber 10 in Step ST2. The processing time of Step ST3 is shorter than the processing time of Step ST2. The ratio of the processing time of Step ST2 to the processing time of Step ST3 was 2. - Then, Step ST2 and Step ST3 were repeated alternately (Step ST4). As a result, a recess RS1 was formed in the first region R1, and a recess RS2 was formed in the second region R2.
- Second Experiment
- The same method as the method of the first experiment was performed except that the process gases in Steps ST2 and ST3 were changed. In Step ST2, instead of the first process gas, a process gas containing a C4F6 gas, a C4F8 gas containing no unsaturated bond, a CH2F2 gas, a krypton gas, and an O2 gas was used. In Step ST3, instead of the second process gas, a process gas containing a C4F6 gas, a C4F8 gas containing no unsaturated bond, a CH2F2 gas, a krypton gas, and an O2 gas was used.
- The ratio of the total flow rate of the C4F6 gas and the C4F8 gas to the flow rate of the CH2F2 gas in Step ST2 was 1.0. The ratio of the total flow rate of the C4F6 gas and the C4F8 gas to the flow rate of the CH2F2 gas in Step ST3 was 1.0.
- Etching Selectivity
- The etching selectivity of the first region R1 and the second region R2 with respect to the mask MK was calculated. The etching selectivity is the etching amount of the first region R1 or the second region R2 with respect to the etching amount of the mask MK. Assuming that the etching selectivity of the first region R1 in the second experiment was 1, the etching selectivity of the first region R1 in the first experiment was 4.89. Assuming that the etching selectivity of the second region R2 in the second experiment was 1, the etching selectivity of the second region R2 in the first experiment was 5.48. Therefore, the etching selectivity in the first experiment was improved as compared with the second experiment.
- Etching Rate
- The etching rates of the first region R1 and the second region R2 were calculated. Assuming that the etching rate of the first region R1 in the second experiment was 1, the etching rate of the first region R1 in the first experiment was 1.09. Assuming that the etching rate of the second region R2 in the second experiment was 1, the etching rate of the second region R2 in the first experiment was 1.09. Therefore, the etching rate in the first experiment was improved as compared with the second experiment.
- Bowing
- Due to the occurrence of bowing, the dimensions of the recesses RS1 and RS2 are increased in parts of the side walls of the recess RS1 and the recess RS2. The maximum value of each of the dimensions of the recesses RS1 and RS2 was set as the bowing dimension. A ratio B/D of the bowing dimension to the depths of the recesses RS1 and RS2 was calculated for the recesses RS1 and RS2. Assuming that the ratio B/D of the recess RS1 in the second experiment was 1, the ratio B/D of the recess RS1 in the first experiment was 0.95. Assuming that the ratio B/D of the recess RS2 in the second experiment was 1, the ratio B/D of the recess RS2 in the first experiment was 0.89. Thus, it is possible to suppress the occurrence of bowing in the first experiment, as compared with the second experiment.
- Etching conditions were selected so that the bowing dimension of the recess RS1 in the second experiment was substantially the same as the bowing dimension of the recess RS1 in the first experiment. Assuming that the bowing dimension of the recess RS1 in the second experiment was 1, the bowing dimension of the recess RS2 in the second experiment was 1.51, and the bowing dimension of the recess RS2 in the first experiment was 1.40. Therefore, in the first experiment, it is possible to suppress not only the bowing of the side wall of the recess RS1 but also to greatly suppress the bowing of the side wall of the recess RS2.
- Effects of Repetition
- In the first experiment, the openings OP1 and OP2 of the mask MK are less likely to be closed in Steps ST2 and ST3, as compared with the second experiment. Therefore, when Steps ST2 and ST3 are repeated alternately in Step ST4, the effect of increasing the etching rate and the effect of suppressing the bowing, as described above, are significantly enhanced.
- Cost
- Also, since the krypton gas is not required in the first experiment, it is possible to reduce the cost as compared with the second experiment.
- From the foregoing description, it will be appreciated that various embodiments of the present disclosure have been described herein for purposes of illustration, and that various modifications may be made without departing from the scope and spirit of the present disclosure. Accordingly, the various embodiments disclosed herein are not intended be limiting, with the true scope and spirit being indicated by the following claims.
Claims (18)
1. An etching method comprising:
(a) providing a substrate on a substrate support in a chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask on the first region and the second region;
(b) etching the substrate with a first plasma generated from a first process gas; and
(c) etching the substrate with a second plasma generated from a second process gas different from the first process gas,
wherein the first process gas contains a Cv1Fw1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond, and
the second process gas contains a Cx1Hy1Fz1 (x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more) gas containing an unsaturated bond.
2. The etching method according to claim 1 , further comprising:
(d) repeating (b) and (c) alternately.
3. The etching method according to claim 1 ,
wherein the first process gas further contains a Cx2Hy2Fz2 (x2 is an integer of 2 or more, and y2 and z2 are integers of 1 or more) gas containing an unsaturated bond,
the second process gas further contains a Cv2Fw2 (v2 is an integer of 2 or more, and w2 is an integer of 1 or more) gas containing an unsaturated bond, and
a ratio of a flow rate of the Cv1Fw1 gas to a flow rate of the Cx2Hy2Fz2 gas is greater than a ratio of a flow rate of the Cv2Fw2 gas to a flow rate of the Cx1Hy1Fz1 gas.
4. The etching method according to claim 3 ,
wherein the ratio of the flow rate of the Cv1Fw1 gas to the flow rate of the Cx2Hy2Fz2 gas is 1 or more and 2 or less.
5. The etching method according to claim 3 ,
wherein the ratio of the flow rate of the Cv2Fw2 gas to the flow rate of the Cx1Hy1Fz1 gas is less than 1.
6. The etching method according to claim 1 ,
wherein the Cv1Fw1 gas contains a fluoromethyl group.
7. The etching method according to claim 6 ,
wherein the Cv1Fw1 gas contains at least one of C4F8 or C3F6.
8. The etching method according to claim 1 ,
wherein the Cx1Hy1Fz1 gas contains a fluoromethyl group.
9. The etching method according to claim 8 ,
wherein the Cx1Hy1Fz1 gas contains at least one of C3H2F4 or C4H2F6.
10. The etching method according to claim 1 ,
wherein the Cv1Fw1 gas contains C3F6, and
the Cx1Hy1Fz1 gas contains C3H2F4.
11. The etching method according to claim 1 ,
wherein a pressure in the chamber in (b) is higher than a pressure in the chamber in (c).
12. The etching method according to claim 1 ,
wherein a processing time of (b) is longer than a processing time of (c).
13. The etching method according to claim 12 ,
wherein a ratio of the processing time of (b) to the processing time of (c) is more than 1 and 3 or less.
14. The etching method according to claim 1 ,
wherein an aspect ratio of a recess formed in the first region and an aspect ratio of a recess formed in the second region in the substrate after the etching method has been applied are equal to or more than 10.
15. The etching method according to claim 1 ,
wherein at least one of the first process gas or the second process gas further contains an oxygen-containing gas.
16. The etching method according to claim 1 ,
wherein at least one of the first process gas or the second process gas further contains an inert gas.
17. The etching method according to claim 1 ,
wherein the mask contains at least one of carbon or boron.
18. A plasma processing apparatus comprising:
a chamber;
a substrate support for supporting a substrate in the chamber, the substrate including a first region having a multilayer film in which a silicon oxide film and a silicon nitride film are alternately stacked, a second region having a single-layer silicon oxide film, and a mask on the first region and the second region;
a gas supply configured to supply a first process gas and a second process gas different from the first process gas into the chamber;
a plasma generator configured to generate a first plasma and a second plasma from the first process gas and the second process gas in the chamber, respectively; and
a controller,
wherein the first process gas contains a Cv1Fw1 (v1 is an integer of 2 or more, and w1 is an integer of 1 or more) gas containing an unsaturated bond,
the second process gas contains a Cx1Hy1Fz1 (x1 is an integer of 2 or more, and y1 and z1 are integers of 1 or more) gas containing an unsaturated bond, and
the controller is configured to control the gas supply and the plasma generator to
etch the substrate with the first plasma, and
etch the substrate with the second plasma.
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
JP2022082922A JP2023170855A (en) | 2022-05-20 | 2022-05-20 | Etching method and plasma processing device |
JP2022-082922 | 2022-05-20 |
Publications (1)
Publication Number | Publication Date |
---|---|
US20230377851A1 true US20230377851A1 (en) | 2023-11-23 |
Family
ID=88768778
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
US18/319,419 Pending US20230377851A1 (en) | 2022-05-20 | 2023-05-17 | Etching method and plasma processing apparatus |
Country Status (4)
Country | Link |
---|---|
US (1) | US20230377851A1 (en) |
JP (1) | JP2023170855A (en) |
KR (1) | KR20230162544A (en) |
CN (1) | CN117096026A (en) |
Family Cites Families (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
JP6328524B2 (en) | 2014-08-29 | 2018-05-23 | 東京エレクトロン株式会社 | Etching method |
-
2022
- 2022-05-20 JP JP2022082922A patent/JP2023170855A/en active Pending
-
2023
- 2023-05-15 KR KR1020230062618A patent/KR20230162544A/en unknown
- 2023-05-16 CN CN202310547870.XA patent/CN117096026A/en active Pending
- 2023-05-17 US US18/319,419 patent/US20230377851A1/en active Pending
Also Published As
Publication number | Publication date |
---|---|
KR20230162544A (en) | 2023-11-28 |
JP2023170855A (en) | 2023-12-01 |
CN117096026A (en) | 2023-11-21 |
Similar Documents
Publication | Publication Date | Title |
---|---|---|
TW202147925A (en) | Plasma processing apparatus and plasma processing | |
US20230377851A1 (en) | Etching method and plasma processing apparatus | |
US20230086580A1 (en) | Etching method and plasma processing apparatus | |
US20230326718A1 (en) | Plasma processing method and plasma processing apparatus | |
WO2024070580A1 (en) | Plasma processing device and power supply system | |
US20240071728A1 (en) | Substrate processing method and plasma processing apparatus | |
WO2024070578A1 (en) | Plasma processing device and power supply system | |
US20230268190A1 (en) | Plasma processing method and plasma processing system | |
WO2023204101A1 (en) | Plasma treatment device and plasma treatment method | |
WO2023127820A1 (en) | Etching method and plasma processing apparatus | |
US20230420263A1 (en) | Etching method and plasma processing apparatus | |
WO2023214521A1 (en) | Plasma processing method and plasma processing apparatus | |
US20240038501A1 (en) | Etching method and plasma processing apparatus | |
JP2024039240A (en) | Etching method and plasma processing equipment | |
WO2022244638A1 (en) | Plasma treatment device and rf system | |
US20220238348A1 (en) | Substrate processing method and substrate processing apparatus | |
US20240030003A1 (en) | Plasma processing apparatus | |
JP2023109496A (en) | Etching method and plasma processing device | |
JP2024013628A (en) | Etching method and plasma processing device | |
JP2022158811A (en) | Etching method and etching device | |
JP2024064179A (en) | Etching method and plasma processing apparatus | |
JP2023109497A (en) | Etching method and plasma processing device | |
TW202245053A (en) | Etching method and etching processing apparatus | |
KR20240047315A (en) | Etching method and plasma processing apparatus | |
JP2024035702A (en) | Plasma processing equipment and plasma processing method |
Legal Events
Date | Code | Title | Description |
---|---|---|---|
AS | Assignment |
Owner name: TOKYO ELECTRON LIMITED, JAPAN Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:YOSHII, FUMIYA;KOMATSU, KENJI;REEL/FRAME:063678/0363 Effective date: 20230516 |
|
STPP | Information on status: patent application and granting procedure in general |
Free format text: DOCKETED NEW CASE - READY FOR EXAMINATION |